Adoption & property issues

We are 3 daughters, am the elder one. My parents adopted my son through registered adoption deed in 2010 who crossed 15 years now. My father was a retired Govt Employee and expired in 2015. since then, my mother is receiving pension, presently it is Rs. 30000 pm. All the 7 properties are his hard earned properties. 1 property is on my son name immediately after adoption. 3 are on my mother name who is a house wife. 1 is on my younger sister bought in 2003 when she was a minor. till the demise of my father, my parents were taken care of adopted son's maintenance. since my father demise, my mother refused to take care of his maintenance. my son is with us now. recently in Sep. 2018, she transferred 2 properties which are on her name to my both sister's daughters one each through a Gift deed. Now my two sisters changed her mind and now they are trying to transfer all the properties. My mother has also recently registered a WILL, the contents we dont know. My father left a paper with his own hand writing without registration stating 5 properties should belongs to adopted son and one each to my sisters. My queries are: 1. As per my knowledge, legal heirs are 5, i.e. my mother, 3 daughters and adopted son. is it correct? 2. Can i take any legal steps for my son's maintenance from my mother? like direction from court for maintenance from her pension etc. 3. Can I take any legal steps for share for me and adopted son in 2 properties which were already transferred? 4. Do I have any recourse to prevent my mother to sell/transfer remaining properties. 5. Do my mother has the right to sell/transfer OR write WILL on the properties earned by my father without considering the legal heirs. 6. My mother is claiming that she is only the legal heir as wife of the demised and owner of all properties and she can transfer/ sell them to any body with out the consent of 3 daughters and adopted son. is this maintainable in the court of law as none of the property was earned by her. 7. Whether the paper written by my father can be taken as valid "Unregistered WILL" and execute that. Point wise reply with relevant legal provisions will be highly solicited.